Vehicle driving simulators, which provide a highly-realistic driving experience, are becoming increasingly affordable. Sophisticated simulators generally employ a simulator master control program which is loaded and run on a host computer system. Slaved to the host computer system is a graphics imaging engine, which generates real-time graphic images in response to control inputs from the host computer system. These images may be projected on a screen which may provide a viewing angle within a range of about 90 degrees to a full 360 degrees in order to create a virtual reality which provides a highly-realistic driving experience. In order to make the simulation as realistic as possible, a simulator may utilize the vehicle cab of an actual production vehicle. Control inputs made by the driver as he manipulates the controls of the vehicle cab are interfaced with the master control program. The perception of reality may be further enhanced with a sound system that produces high-fidelity sounds and a motion system coupled to the cab which subjects the driver to forces, all consistent with the projected images of the outside environment, the road surface, and driver inputs. A high-end driving simulator may even generate tire noise appropriate for the imaged road surface. Purchasers of vehicle driving simulators generally have one or more specific applications for the simulator. For example, it may be used to train semi-truck drivers, it may be used to teach high-speed pursuit skills to police officers, or it may be used to improve the safety skills of emergency vehicle drivers. In order to enhance the assimilation of driving skills for such specialized uses, it is highly desirable to use the vehicle cab of the actual vehicles which will be driven on the job. This complicates the manufacture of the simulators, as there are literally dozens of possible vehicle cabs which must be interfaced to the simulator software. For example, one police department may wish to use a Ford Crown Victoria cab for its simulator, while another may desire to use a Chevrolet Lumina cab. The situation is further complicated by the fact that governmental agencies, such as police departments, typically change vehicles every two to three years. In addition, truck driving schools may wish to utilize several truck cabs to improve the transferability of learned skills to the real world.
The vehicle driving simulation industry, though in its infancy, is highly competitive. A simulator manufacturer can improve profitability by keeping hardware inventories to a bare minimum and by meeting the needs of the greatest number of customers with the fewest number of separate product lines. Ideally, a single basic product line would be easily customizable to meet the needs of all customers.
Software changes can implement many of the differences in simulating different types of vehicles, but at some point the software must connect to each cab's unique electrical circuitry through a hardware interface. Some of the differences between individual cab's electrical instrumentation may include:
1. Voltage ratings; PA1 2. Input signal waveform requirements; PA1 3. Switch logic, such as seat belt switches being open or closed when fastened. PA1 4. Number of input and output signals; and PA1 5. Types of sensors on the steering wheel, brake pedal, accelerator pedal, or gear shift lever. (i.e. resistive potentiometers, optical encoders, switches, etc.)
The current art addresses these differences in a variety of ways. FIGS. 1 through 3 represent three approaches now used to interface a vehicle cab to a simulator system having a display screen 101, a projector 102 for projecting images on the screen 101, and a simulator data processing unit 103. The first interface approach is represented by FIG. 1. Using this approach, the cab 105 is completely rewired for connection to a standard interface unit 104. The primary advantage of this approach is there are no software changes from one cab to another. The major disadvantage, though, is that the rewiring process is costly and time-consuming. This is particularly true if the job requires the customization of switches and instrumentation.
The second approach, represented by FIG. 2, is to design unique interface circuitry 204 for each cab 205 which interconnects the standard cab wiring with the simulator data processing unit 103. The main advantages of this option are that no changes need be made to either the simulation software or to the cab wiring. There are several significant disadvantages to this approach, however. Much time will be spent not only in the analysis and documentation of the cab circuitry, but in the design and manufacture of the custom interface circuitry. Additionally, as the custom interface circuitry will be built in limited quantities, the manufacturing costs will be relatively high. A further disadvantage is the need to reanalyze and document cab circuitry and redesign and manufacture new interface circuitry each time a different vehicle cab is introduced.
Another approach frequently used in the simulation industry is represented by FIG. 3. An interface 304 is designed using existing off-the-shelf circuit boards and electronic modules. Such an approach typically requires that changes be made to the simulation software. The primary advantage to this approach is that less custom hardware is required. By using readily-available boards and modules, not only are design and manufacturing costs are reduced, but maintenance costs as well. There are many problems with this approach. The off-the-shelf circuit boards are typically expensive and difficult to integrate into the system. They may also be difficult to program. In addition, if the software is redesigned, the boards must generally be replaced. Also significant are the time and costs associated with reverse engineering (i.e., analyzing and documenting) the cab circuitry. If software changes are required, this will add to the cost. This option may not even be available for some cabs, for they are so unique that they require custom-designed interface hardware.
None of the interface options heretofore described lends itself to the rapid and economical interfacing of a cab to a simulator system. Simulator customers want to be able to change cabs periodically and want to minimize down time and costs related to those changes. Although the interface option of FIG. 1 permits rapid swapping of cabs and minimal costs related to the actual swap, the cost of providing the standard interface at the cab is substantial.
What is needed is an interface which will reduce the cost of connecting a vehicle cab to a driving simulator, and which will permit a simulator owner to swap cabs on his simulator much more quickly, much less expensively, and with far fewer software changes than would be possible using current cab interfaces. Such an interface will facilitate the swapping of vehicle cabs by requiring only simple electrical disconnections and connections and minor software modifications. In addition, it would be helpful if debugging of the new simulator hardware-cab combination were facilitated by the new interface.